Method and apparatus for reading under sampled bar code symbols

Abstract

The present invention is directed to a method for reading a bar code symbol with an optical reader. The method includes the step of scanning the bar code symbol to obtain a plurality of scan lines. Each of the plurality of scan lines includes a linear array of N-pixel values. Adjacent pixels in the linear array of N-pixel values are separated by a sample separation distance. A reconstructed scan line is generated that interleaves the N-pixel values from selected scan lines of the plurality of scan lines. A reconstructed pixel sample separation distance of adjacent interleaved pixels is an integer fraction of the pixel sample separation distance.

Description

CROSS REFERENCES TO RELATED APPLICATIONS [0001] The present application claims the priority, under 35 U.S.C. § 119 of U.S. Provisional Patent Application No. 60 / 526,366 filed Dec. 2, 2003. The disclosure of the above provisional application is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION [0002] The present invention relates generally to bar code readers, and particularly to bar code readers with improved spatial resolution. DESCRIPTION OF THE PRIOR ART [0003] Many bar code readers have the ability to optically resolve bar code symbol features having narrow symbol elements. However, the bar code reader may not have sufficient spatial resolution to actually capture these narrow symbol elements. Those of ordinary skill in the art will recognize that insufficient spatial resolution is very different in nature than insufficient optical resolution. The bar code reader must have adequate optical resolution and adequate spatial resolution to read a bar code s...

AI Technical Summary

Benefits of technology

[0007] The present invention addresses the needs described above. The present invention provides a system and method for reconstructing a high resolution scanning line from a plurality of under-sampled, degraded, or noisy scan lines. Thus, the present invention also opens up the possibility of substituting expensive, high resolution imaging components with cruder and cheaper imaging components.

Problems solved by technology

However, the bar code reader may not have sufficient spatial resolution to actually capture these narrow symbol elements.

A lack of either one may result in a non-read.

Insufficient spatial resolution may result when the pixel sample separation is greater than or substantially approaches the width of the image of the narrowest bar code symbol feature.

First, the bar code reader may be positioned at an excessive distance from the bar code symbol.

This problem may be exacerbated by the need for a wide field of view in close proximity to the scanner.

Second, bar code symbols are becoming increasingly smaller.

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